Reactor with an external neutron source for safe nuclear power and the possibility of making a model of an electronuclear apparatus

The possibility is discussed of constructing a 200-MW nuclear power installation utilizing a high-temperature gas-cooled subcritical reactor, in which a chain reaction is initiated by an external neutron source. Such a source can be obtained by irradiating targets made of various substances with an intense beam of charged particles accelerated in a linear rf accelerator. The reactor and the accelerator are located in an underground chamber. A working physical model of an electronuclear apparatus can be used to demonstrate the basic possibilities of making the installation and to experimentally verify the scientific and technical solutions for its construction. Equipment available at the A. N. Krylov Central Scientific-Research Institute and the D. V. Efremov Scientific-Research Institute of Electrophysical Apparatus make it possible to construct a model of the electronuclear apparatus over a period of several years with a minimum of expenditure. D. V. Efremov Scientific-Research Institute of Electrophysical Apparatus. A. N. Krylov Central Scientific-Research Institute. Translated from Atomnaya énergiya, Vol. 87, No. 2, pp. 101–108, August, 1999.     

Determination of the ionization and charge-transfer cross sections in interactions of fission fragments with helium and argon atoms

Conclusions Experimental data on the differential cross section of electron emission from helium and argon atoms with respect to the electron energy during bombardment by fission fragments were obtained under conditions of low data acquisition rate and high background level due to concomitant particles. The results were compared with a theoretical calculation of the ionization and charge-transfer cross sections of helium and argon atoms by the method of classical trajectories in the collision studied and attest to a good agreement between experiment and the proposed theoretical model. This work was supported by the Russian Foundation for Fundamental Research under projection No. 96-02-17443a. Joint Institute of Nuclear and Thermal Power Production, V. A. Rykov, Main Science Center of the Russian Federation — A. I. Leipunskii Physics and Power Engineering Institute. Translated from Atomnaya énergiya, Vol. 84, No. 1, pp. 29–34, January, 1998.     

The 70 kA pyrobreaker for ITER magnet back-up protection

The paper presents the results of development and testing of an explosively actuated circuit-breaker (the so-called pyrobreaker) designed and manufactured at the Efremov Institute [1]. In accordance with the ITER specifications this switch will be used for continuous operation with DC currents up to 70 kA and shall be capable, on command, to transfer this current to a resistive load under a voltage up to 10 kV in less than 1 ms.A number of current commutation tests have been carried out on several prototypes [2]. The last experimental campaign has demonstrated reliable operation of the pyrobreaker with 20% safety margin for the interrupted current and 100% margin for the recovery voltage relative to the ITER requirements.Besides, peak current withstand tests have been performed with pulse currents up to 420 kA generated by the unipolar current generator available at the Efremov Institute.     

New model of equiaxial growth of uranium dioxide grains under irradiation conditions

Conclusions The experimental data give evidence of a retardation in the growth of equiaxial grains when oxide fuel is irradiated. This retardation in grain growth can be explained as being due to the formation of short-lived defect structures on the grain boundaries under the action of irradiation. An analysis of a broad spectrum of experimental data indicates that a model based on this hypothesis correctly predicts the growth of equiaxial grains in a wide range of temperatures, irradiation intensities, and fuel depletions. The work was carried out with the partial support of the Russia Fund for Fundamental Research under grant number 96-02-18686. State Scientific Center of the Russian Federation, Institute of Innovative and Thermonuclear Research, Troitsk. Translated from Atomnaya énergiya, Vol. 84, No. 4, pp. 329–334, April, 1998.     

Manufacturing,testing and post-test examination of ITER divertor vertical target W small scale mock-ups

ENEA is involved in the International Thermonuclear Experimental Reactor (ITER) R&D activities. During the last years ENEA has set up and widely tested a manufacturing process, named Hot Radial Pressing (HRP), suitable for the construction of high heat flux plasma-facing components, such as the divertor targets.In the frame of the EFDA contract six mock-ups were manufactured by HRP in the ENEA labs using W monoblocks supplied by the Efremov Institute in St. Petersburg, Russian Federation and IG CuCrZr tubes.According to the technical specifications the mock-ups were examined by ultrasonic technique and after their acceptance they were delivered to the Efremov Institute TSEFEY-M e-beam facility for the thermal fatigue testing. The test consisted in 3000 cycles of 15 s heating and 15 s cooling at 10 MW/m² and finally 1000 cycles at 20 MW/m².After the testing the ultrasonic non-destructive examination was repeated and the results compared with the investigation performed before the testing.A microstructure modification of the W monoblock material due to the overheating of the surfaces and the copper interlayer structure modification were observed in the high heat flux area.The leakage points of the mock-ups that did not conclude the testing were localized in the middle of the monoblock while they were expected between two monoblocks.This paper reports the manufacturing route, the thermal fatigue testing, the pre and post non destructive examination and finally the results of the destructive examination performed on the monoblock small scale mock-ups.     

ACCELERATOR-BASED ATOMIC PHYSICS AT THE LAWRENCE BERKELEY LABORATOTY:COLLISIONS OF FAST,HIGHLY-CHARGED IONS WITH ATOMS

Research on accelerator-based atomic physics at the Lawrence Berkeley Laboratory super-HILAC and Bevalac accelerators is described. This research covers several important topics in collisions of fast, highly charged ions with atoms: charge transfer, ionization, and excitation. Multiple - electron processes are emphasized. Electron correlation is important in some of these processes, e.g., resonance transfer and excitation (RTE) multiple-electron capture in close collisions. A variety of experiments and results for energies from 1 to 420 MeV/u are presented.     

A cyclotron with a spatially varying magnetic field

This article is devoted to the design of a cyclotron with a spatially varying magnetic field. The basic conclusions of the linear theory of motion of charged particles in a magnetic field of periodic radial and azimuthal structure are given. The theoretical and experimental results of the study of nonlinear resonance close to the center of the accelerator are presented. Formulas are obtained for the calculation of required magnetic field configurations. Methods of shimming, measurement, and stabilization of the magnetic field are suggested. An accelerator designed with pole faces of diameter 120 cm was used for modeling the ion phase motion and for investigating spatial stability. Deuterons were accelerated to an energy of 13 Mev at an accelerating voltage of 5 kv.A brief account of the starting up of this accelerator appeared in the journal Atomnaya Energiya6, 6, 657 (1959). [Original Russian pagination. See. C. B. translation]The authors highly appreciate the great amount of work and effort on the part of the personnel of the experimental shop, designing office, electronic and electrical departments of the Nuclear Problems Laboratory of the Joint Institute of Nuclear Studies. The authors are deeply grateful to these personnel and to their chiefs K. A. Baicher, N. I. Frolov, M. F. Shul'ga, F. V. Chumakov for their aid, valuable discussions, and suggestions in solving many technical problems. The authors express their gratitude to D. I. Blokhintsev, D. V. Efremov, K. N. Meshcheryakov, V. N. Sergienko for constant interest and assistance, which greatly facilitated the work, to E. G. Komar, I. F. Malyshev, L. N. Fedulov for constructing and preparing the chamber and the magnet of the accelerator, to A. V. Chestnyi for help during the first stage of setting up the technical problem.     

Transmutation of long-lived radioactive wastes from nuclear power

Conclusion The need to provide ecologically clean and safe nuclear power in the future requires intensive study of a wide range of technological problems today. The most important one is the reprocessing of radioactive nuclear plant wastes through atomic transformation. Whether there will be transmutation plants based on more or less traditional varieties of power reactors, or whether there will be hybrid systems using powerful accelerators, will be shown by further developments, and not just in the field of the physics and technology of reactors and accelerators. A thorough examination should be conducted at every stage of the fuel cycle, using data from radiochemistry, biology, economics, and possibly other disciplines. However, it is already clear that the complex problems of creating an ecologically clean and safe form of power production, in view of their worldwide scale, can be solved only by international efforts based on the close cooperation of specialists from various countries.Institute of Theoretical and Experimental Physics. Translated from Atomnaya Énergiya, Vol. 70, No. 6, pp. 380–386, June, 1991.     

Differential ionization cross-sections for nitrogen and carbon dioxide molecules bombarded by fission fragments

Conclusions Previous experimental data on electron-emission cross-sections, doubly differentiated with respect to emission angle and electron energy, which were obtained from bombarding molecules of nitrogen and carbon dioxide gas with fission fragments, were used to calculate iodization cross-sections, differentiated only with respect to angle and only with respect to electron energy. The results were compared with theoretical [2–4] calculations and showed a large (factor of ∼10) difference between calculation and experiment. The calculated results depend strongly on the model equations for the electron velocity in the atom. The authors express their thanks to L. V. Egorovaya and A. I. Chusov for help in doing the work, and also to A. P. Budkin and Yu. V. Sokolov for discussions of the results. This work was supported by the Russian Fund for Fundamental Research, Project No. 96-02-17443a. Russian Federation State Science Center, A. I. Leipunskii Institute of Physics and Power Engineering, Obninsk. Translated from Atomnaya énergiya, Vol. 83, No. 4, pp. 273–276, October, 1997     

Design development and analytical assessment of LLCB TBM in Russian Federation during 2012–2013

The activity on the design, analysis, and R&D for the test blanket module (TBM) with lead–lithium (LL) eutectic coolant and ceramic breeder (CB) was performed in the Russian Federation (RF) according to the technical program of cooperation between the leading research institutes of India (“leader” of the LLCB TBM concept) and RF (“partner”). During the period of 2012–2013, the joint efforts of the RF and Indian specialists were focused on the development of the TBM's basic design with an optimal set of parameters (in particular for testing on both H-H and H-D operation phases of International Thermonuclear Experimental Reactor (ITER) machine). This article briefly describes the results of the TBM design and analysis that have been obtained by the RF specialists (“NIKIET” and D.V. Efremov Institute) in support of the LLCB concept (both DEMO blanket and TBM itself). The main directions of this activity in RF institutes were as follows:

• –development of the TBM design taking into account the ability to manufacture the TBM elements (load-bearing casing, tritium-breeding zone, and attachment system);
• –thermal analysis (in both stationary and transient approaches) of TBM design options (four variations of helium and eutectic flowing directions);
• –structural analysis of TBM design elements for Inductive I operation mode; and
• –recommendations (based upon the results of comparative analysis) on the reference design to be used on further stages of concept development.

The critical issues and further plans on the development of LLCB TBM and corresponding DEMO blanket in the RF are also presented in this article.     

Evaluation of mean time between accidental interruptions for accelerator klystron systems based on the reliability engineering method

Frequent beam trips as experienced in existing high-power proton accelerators may cause thermal fatigue in Accelerator-Driven System components. In order to overcome the beam-trip problem, the beam-trip frequencies were estimated based on operational data on existing accelerators. However, there are at least three methods to calculate the mean time between accidental interruptions (MTBI) for one of the accelerator components, the klystron system. In this study, the four types of MTBI for the klystron systems of an electron/positron injector linear accelerator at the High Energy Accelerator Research Organization were compared based on the same operational data. In the analysis, the stop events of the klystron systems were classified, and the MTBI for the klystron systems was calculated using the Kaplan–Meier (KM) estimation, which is a representative non-parametric reliability method. As a result, the mean value of the MTBI found by the KM estimation was 57.3 ± 6.5 hours. On the other hand, the mean values of the MTBI found by the three traditional methods were 30.9 ± 2.4, 32.0 ± 2.3, and 50.4 ± 5.9 hours. The mean values for the ratios of the MTBI found by the KM estimation, to the MTBI found by the traditional estimation, were 1.67 ± 0.07, 1.58 ± 0.06, and 1.14 ± 0.01, respectively. Although these results are obviously different from traditional results, it appears that the present estimation is suitable for the MTBI for accelerator components.     

Fail-Safe Circuits for Nuclear Protective Systems

The article describes a new set of fail-safe logic blocks particularly suited to safety systems. The input information is normally +5V; in case of alarm, the input drops to 0V. Fundamental blocks (AND, OR, NOT, etc.) are pulse-modulated, so as to achieve 0V output voltage in case of failure. More complex logic function can be synthesized and redundancy can be employed in order to avoid erroneous action.     

Research activities for accelerator-driven transmutation system at JAERI

Japan Atomic Energy Research Institute (JAERI) performs Research and Development (R&D) for accelerator-driven systems (ADS) for transmutation of long-lived nuclides. To study the basic characteristics of ADS, Transmutation Experimental Facility is proposed within the framework of the J-PARC project. The facility consists of two buildings, Transmutation Physics Experimental Facility to research the neutronics and the controllability of ADS and ADS Target Test Facility for material irradiation and partial mockup of beam window. A comprehensive R&D program for future ADS plant is also underway in three technical fields, 1) accelerator, 2) lead-bismuth target/coolant and 3) subcritical core.     

Particle generation at very high energies

Values are obtained for the intensities of beams of various particles, including -quanta, neutrinos, and -mesons, formed in inelastic particle interactions in the energy range 1–10³ Bev. These values may be useful in designing accelerators for very high energies.We are grateful to I. Silin, an assistant at the Calculational Center of the Joint Institute of Nuclear Studies for the large amount of assistance rendered in making the calculations, as well as to V. I. Veksler for his critical comments and valuable advice, much of which was made use of in our calculations. We are especially happy to thank D. I. Blokhintsev and M. A. Markov, on whose initiative our calculations were made, for numerous discussions on very high energy particle interactions.     

High-energy nuclear physics and nuclear astrophysics at the Radium Institute

Research into high-energy nuclear physics and nuclear astrophysics at the Radium Institute is briefly reviewed. The history of cosmic-ray research is outlined, from the early years of the Institute, as well as the history of research on high-energy physics. The basic work on nuclear astrophysics, cosmochronology, and astrochemistry is described. Research at the Institute on direct nuclear reactions, nuclear fragmentation and multifragmentation, deeply inelastic nuclear processes, nuclear fission at high exciting energies, nuclide formation at the limit of stability, multiple particle formation in relativistic internuclear reactions, and other topics is considered. Scientific and methodological accomplishments are noted. V. G. Khlopin Radium Institute. Translated from Atomnaya énergiya, Vol. 86, No. 6, pp. 419–426, June, 1999.     

小型粒子加速器人身安全联锁系统设计与实现

20世纪30年代以来,世界上运行中的粒子加速器已超过3万台,其中用于科研的大型粒子加速器有200台左右。粒子加速器在运行过程中会产生对人体有害的电离辐射,为保障工作人员在联锁控制区内的人身辐射安全,避免出现辐照事故,需建立一套人身安全联锁系统。本文利用全硬件、模块化的设计思想,基于PLC、置换型机械联锁钥匙、自主研制的急停/巡更装置及摄像监控等一系列硬件设备,专门为小型粒子加速器研制了人身安全联锁系统。该系统在加速器驱动的次临界系统（ADS）注入器Ⅰ和中国科学院高能物理研究所（IHEP）加速器电子标定束线装置两个项目中至今运行稳定可靠,并可推广应用于工业辐照装置。     

Charge equilibrium of fission fragments after emergence from a solid into gas

Conclusions The charges of fission fragments in a two-group approximation were obtained by means of an experimental apparatus that made it possible to measure the charge of fission fragments by the method of deflection in a magnetic field under the conditions of both a high vacuum and a low-pressure gas and the transition to the state of charge equilibrium in the gas was investigated. The role of the density effect at low pressure was also clarified, and the electron capture cross section of fission fragments on the initial section of a track were estimated. The method developed makes it possible to perform further investigations of the charge states of fission fragments in a gas with the energy of the fragments decreasing along a track without making a priori assumptions about the relation between the ion charges and the velocity of the particles. I thank L. V. Egorova and A. I. Chusov for assisting in this work. This work was supported by the Russian Fund for Fundamental Research, project No. 96-02-17443a. Main Science Center of the Russian Federation — A. I Leipunskii Physics and Power Engineering Institute. Translated from Atomnaya énergiya. Vol. 83. No. 1, pp. 12–17, July, 1997.     

Development of the armoring technique for ITER Divertor Dome

This paper describes the current status of the technique for armoring of Plasma Facing Units (PFUs) of the ITER Divertor Dome with flat tungsten tiles planned for application at the procurement stage.Application of high-temperature vacuum brazing for armoring of High Heat Flux (HHF) plasma facing components was traditionally developed at the Efremov Institute and successfully tried out at the ITER R&D stage by manufacturing and HHF testing of a number of W- and Be-armored mock-ups [1], [2]. Nevertheless, the so-called “fast brazing” technique successfully applied in the past was abandoned at the stage of manufacturing of the Dome Qualification Prototypes (Dome QPs), as it failed to retain the mechanical properties of CuCrZr heat sink of the substrate. Another problem was a substantially increased number of armoring tiles brazed onto one substrate. Severe ITER requirements for the joints quality have forced us to refuse from production of W/Cu joints by brazing in favor of casting.These modifications have allowed us to produce ITER Divertor Dome QPs with high-quality tungsten armor, which then passed successfully the HHF testing. Further preparation to the procurement stage is in progress.